In a magnetic rigid disk storage device, a rotating disk is employed to store information in small magnetized domains strategically located on the disk surface. Rigid disk storage devices typically include a frame to provide attachment points and orientation for other components, and a spindle motor mounted to the frame for rotating the disk. A magnetic read/write head is usually provided as part of a "head slider" to be positioned in close proximity to the rotating disk, which enables the creation and reading of the magnetic domains on the disk. The head slider is supported and properly oriented in relationship to the disk by a head suspension which provides forces and compliances necessary for proper slider operation. As the disk in the storage device rotates beneath the head slider and head suspension, the air above the disk similarly rotates, thus creating an air bearing which acts with an aerodynamic design of the head slider to create a lift force on the head slider. The lift force is counteracted by the head suspension, thus positioning the head slider at a height and alignment above the disk which is referred to as the "fly height."
Typical head suspensions include a load beam and a flexure. The load beam normally includes a mounting region at a proximal end of the load beam for mounting the load beam to an actuator arm of the disk drive, a rigid region, and a spring region between the mounting region and the rigid region for providing a spring force to counteract the aerodynamic lift force acting on the head slider described above. Stiffening rails can also be provided on the rigid region of the load beam. The flexure is located at a distal end of the load beam, and can be either integral with the load beam, or it can be formed as a separate piece which is rigidly mounted on the load beam using conventional means such as spot welds. The flexure typically includes a cantilever region having one or more free ends where the head slider is mounted and thereby supported in read/write orientation with respect to the rotating disk. The free end of the cantilever region is resiliently moveable with respect to the remainder of the flexure (described in greater detail below) in response to the aerodynamic forces generated by the air bearing. Other types of flexures include connecting portions or bridges between a slider mounting portion of the flexure and the remainder of the flexure or load beam, wherein the slider mounting portion of the flexure moves in response to the aerodynamic forces.
Certain types of head suspensions include a generally spherical dimple having a convex surface formed in either the load beam or the cantilever region of the flexure. Such dimples can act as a "load point" between the flexure/head slider and the load beam, and dimples designed to serve this purpose are referred to as "load point" dimples. The load point dimple can be formed in the load beam of a head suspension so that the convex surface of the dimple contacts a surface of the cantilever region of the flexure where the head slider is mounted, or the dimple can be formed in a surface of the cantilever region of the flexure so that its convex surface contacts the load beam. A load point dimple provides clearance between the flexure and the load beam, and serves as a point about which the head slider can gimbal in response to the aerodynamic forces generated by the air bearing. Variations in the rotating disk create fluctuations in these aerodynamic forces. The aerodynamic forces cause the head slider to roll about a longitudinal axis of the head suspension, and to pitch about an axis planar with the head suspension but perpendicular to the longitudinal axis. The load point dimple serves as the pivot point about which the flexure and head slider gimbal in response to the pitch and roll aerodynamic forces.
Disk drives are being designed having smaller disks and closer spacing, and as such, smaller and thinner head suspensions are required. These smaller suspensions have a corresponding smaller load beam and a smaller flexure and slider mounting region in which to form load point dimples. As such, the load point dimples formed in the load beam or flexure are reduced in size. With spherical dimples, however, there is a limit as to how small load point dimples can be. For example, as the radius of a spherical load point dimple is reduced, the clearance between the flexure and the load beam which is necessary for the head slider and flexure to gimbal about the pitch and roll axes is likewise reduced, as compared to dimples having like spherical portions. However, this spacing needs to be sufficient to prevent the flexure/head slider from contacting the load beam as it gimbals.
Moreover, because of the gradual transition of a dimple from the plane of the load beam or flexure where it is formed, spherical dimples can be difficult for optical systems to locate. Optical and vision systems are known to be used to mount and align head sliders to flexures, and it is critical to such systems that they can locate load point dimples in order to ensure proper location and alignment of the head slider. The spherical shape of current dimples does not create a sharply defined profile that is easily sensed by an optical system.
Additionally, certain operations performed during the manufacture of a head suspension can slightly deform the load point dimple's position and attitude, which can be measured or indicated by a deflection angle in the surface in which the spherical load point dimple is formed. These operations specifically include for example forming the stiffening rails on the load beam, which can create a "twist" and/or curvature in the load beam that leads to an out-of-plane condition at the load point dimple, and forming the load point dimple itself, which can create a deflection angle through uneven material deformation. In addition, when under load, the load beam of the head suspension may also deflect, which can create a deflection angle or which can cause a change in a deflection angle already present in surface in which the load point dimple is formed. This deflection angle can shift the contact point between the load beam and the flexure provided by the spherical load point dimple, which may also negatively affect the performance of the head suspension.